Modern document examiners not only determine authorship and authenticity but they use the latest technology to detect changes, resurrect evidence, recover entire documents, and analyze DNA.
This article is the second and final part of a series on forensic document evidence, which can be found in virtually every fraud investigation. Adapted from a presentation at the ACFE's 13th Annual Fraud Conference, the authors developed it in close cooperation with the Miami-Dade (Florida) Police Department Crime Laboratory. - ed.
In the January/February issue, we discussed traditional questioned document examinations including methods of handling documentary evidence and selecting a qualified document examiner. Modern document examiners have broad abilities beyond the traditional authorship and authenticity determinations. They can, for example:
- detect alterations, erasures, and obliterations;
- resurrect evidence deteriorated by fading or decomposition; and
- recover entire documents, or portions of documents, from underlying pages, which were present when the original document was written.
Document examiners use such equipment as the Video Spectral Comparator, Raman Spectral Comparator, and Electrostatic Detection Apparatus.
Video Spectral Comparator
Ink fluoresces under certain ranges of light, which are invisible to the naked eye. The Video Spectral Comparator (VSC) uses filters to vary the light bombarding the document. The document is viewed through a camera and computer monitor. As the wavelength of the light is varied, the picture changes.
When a subject makes an alteration on a document he often uses a different pen from his original writing. Varying inks may appear to be the same color to the naked eye or even under magnification. But they will fluoresce differently and reveal two writing samples made with two different pens at two different times.
Fluorescence is also used to detect deteriorated, obscure, indecipherable, or invisible evidence. In one landmark case, the Miami-Dade Police Department Crime Laboratory was able to recover a telephone number written on a murder victim's palm. (See Exhibits 1 and 2.) The number could not be read with the naked eye or with magnification, but it fluoresced under the VSC. When investigators went to the address to which the number was traced, the murderer opened the door and confessed.